A constrained intrinsic cohesive finite element method with little stiffness reduction for fracture simulation

• The stiffness reduction problem induced by cohesive surfaces is solved.
• The efficiency the cohesive finite element is significantly improved.
• The basic features of dynamic fracture are well captured.

To solve the stiffness reduction problem caused by cohesive surfaces in the intrinsic cohesive finite element model (CFEM), a series of constraint conditions are introduced into the algebraic equation system of the CFEM to constrain the separation of cohesive surfaces. To make the constrained cohesive surfaces active at the appropriate time, the constraint conditions will be removed in the high stress zone where fracture could initiate and propagate. The efficiency of the constrained CFEM, instead of being reduced by the constraint conditions, is significantly improved because the constrained cohesive surfaces are not counted in the numerical implementation.